Management Control Points Related to the Lag Phase of Fungal Growth in a Stored Rapeseed Ecosystem

Abstract

The quality of rapeseed oil largely depends on the quality of postharvest preservation of raw seeds. Fungal infestation at early stages of the storage of rapeseeds is a major cause of their spoilage. The knowledge of relations between the storage conditions, fungal contamination, and technological quality of rapeseeds is essential to specify key control points that can be used to improve postharvest management systems and maintain rapeseed quality. The aim of this study was to define decisive control points on the basis of the kinetics of early mold growth in ecosystems of rapeseeds in a hazardous initial microbiological state, stored under various water activity and temperature conditions (a w =0.78-0.96 and t =12-30 C). A correlation between the acid value (AV), germination, and fungal infestation of seeds was found in ecosystems with significant mold activity. The analysis of the mold growth kinetics with regard to AV, seed germination, and visible mold time showed that the detection of early (invisible) fungal growth could be a good basis for determining the time during which rapeseeds should be protected from deterioration. The research results showed how to use the length of the lag phase to identify decisive control points, which are necessary to improve the existing control systems of rapeseed preservation and storage.

Changes in contents of phenolic compounds (sinapic acid derivatives) in seeds of Brassica napus L.under adverse storage conditions

“…the lag phase, exponential growth and the stationary phase. A similar pattern of mould development was observed in barley grain and rapeseed ecosystems by Wawrzyniak et al (2013;2018a;2018b). The decrease in CFU of moulds in the initial period of seed storage (in the lag phase of mould growth) was associated with the fungi's adaptation to environmental conditions.…”

“…While investigating the rapeseed ecosystem with a moisture content of 13.1% w.b. stored at 24°C, Wawrzyniak et al (2018a) also observed the beginning of fungal activity after 6 days of storage, whilst the stationary phase of the mould development began after 18 days.…”

“…Humidity and temperature conditions for seed storage were selected based on previous studies on the kinetics of mould growth in rapeseed ecosystems and changes in the technological quality of seeds stored under various temperature and humidity conditions (Wawrzyniak et al, 2018a). According to the studies cited, the seed storage conditions applied in this experiment promote activation of fungal microflora and cause an increase in free fatty acid content; nevertheless, after 21 days of storage seeds still retain adequate technological quality.…”

“…The scope of adverse chemical and biochemical changes occurring during rapeseed storage is determined first of all by their excessive moisture content. Increased seed moisture content significantly reduces safe storage time, causing the risk of mould development (Pronyk et al, 2006;Wawrzyniak et al, 2018a) and rapeseed contamination with secondary metabolites of these microorganisms, i.e. mycotoxins, exhibiting toxicity in relation to humans and animals (Hussein and Brasel, 2001).…”

The quality of cold-pressed rapeseed oil obtained from seeds of Brassica napus L. with increased moisture content

“…It may be utilized for consumption, in the food industry or for non-food purposes. The production of rapeseed in the European Union has exceeded 20 million tons/year and accounts for about 30% of global oilseed production (Wawrzyniak et al, 2018). Rapeseed oil, due to its fatty acid composition, is considered to be one of the healthiest vegetable oils.…”